With modified analytical embedded atom method (MAEAM), the energies of twist grain boundaries (GBs) have been calculated for three noble metals, Cu, Ag and Au with the same FCC structure. The results are similar for all the three metals: (1) the unrelaxed energies keep almost constant with twist angles θ; (2) after expansion perpendicular to the boundary, GB energies drop significantly to less than one-third of their surface energies respectively; (3) in-boundary translation results in periodic energy variation with the period of LS/S, but the energy variation is slight.